JPS60247024A - Method and apparatus for monitoring air fuel ratio in operation of internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for monitoring the air-fuel ratio in an internal combustion engine, and also to an apparatus for controlling the air-fuel ratio.

[Prior Art and Problems to be Solved by the Invention] Detection of abnormal conditions in the air-fuel ratio of an internal combustion engine is mostly performed by the user, who has an experiential and subjective system linked to the driver's sensitivity. Corrections to deal with the abnormal conditions are often made by manual adjustments by skilled personnel.

PublicationsCentro R1e@rche Fiat (
SAW technical peno f-series 4830498.
(March 28, 1983), which relates to an accelerometer device arranged to communicate anomalies by measuring the lateral movement of an engine. This device is
At present, it can only be applied to bench test engines, since a car driving on the road is subject to vibrations, which could impede the reliability of the aforementioned measurements. Because it will be.

Previously used systems include systems based on the detection of fuel fluctuations, in particular on the detection of pressure cycles within the combustion chamber by means of pressure sensors suitably placed within the combustion chamber.

However, this method is also difficult to apply industrially, because if long-term reliability is required, senna is expensive) and the combustion of the sensor is difficult. Installation in the chamber requires difficult processing.
This is because it is uneconomical.

Programmed microprocessor systems are known to ensure that the air/fuel ratio is maintained within the stoichiometric value based on the sum of on and off signals provided to the sensor. However, the sensor is typically composed of zirconium dioxide and titanium dioxide. Such a system is used in floor desks to thoroughly reduce air pollution exhaust gas, and the air pollution exhaust gas reduction is performed using a muffler equipped with a three-way catalyst, and the muffler equipped with the three-way catalyst is It operates accurately under maximum efficiency conditions when measurements are maintained within a limited window around the stoichiometric value. However, these systems do not allow adjustment of measurements within the lean air-fuel mixture range, where the sensor detects chemical changes that occur near the stoichiometric air-fuel ratio value condition. It is only possible to do so.

Under lean air-fuel mixture conditions, the sensor does not have sufficient sensitivity to provide reliable air-fuel ratio detection.

It is an object of the present invention to provide a method and apparatus for performing air-fuel ratio control in an internal combustion engine, and also for monitoring and self-correcting the air-fuel ratio when the air-fuel mixture has an irregular air-fuel ratio. The object of the present invention is to provide a method and apparatus for doing so.

The device according to the invention is particularly adapted to generate a signal substantially proportional to the air-fuel ratio in the control of lean air-fuel mixtures (air-fuel ratio greater than 16), wherein the lean air-fuel mixture Under mixture conditions (lean air-fuel mixture), fluctuations in the air-fuel ratio result in considerable disturbances to periodic fuel fluctuations and therefore to the smoothness of operation of the engine itself. These disturbances to periodic fuel fluctuations cause pressure fluctuations in the intake manifold to
It is caused only to a degree proportional to the air-fuel ratio fluctuation.

[Means for solving problems]

In the present invention, the aforementioned object is achieved by virtue of the fact that the invention concerns a method for monitoring the presence of anomalous combustion phenomena, and thus indirectly the presence of fluctuations in the air-fuel ratio. In order to measure the air pressure in the intake duct during engine operation, to measure the fluctuations from one cycle to the next caused by irregular combustion phenomena. In the step of processing the pressure signal, in the step of storing a predetermined value in correspondence with the optimum operating value, when the value corresponding to the measured pressure fluctuation deviates from the stored value, an irregular phenomenon exists in the air-fuel ratio. and correcting the air-fuel ratio.

The invention also relates to a device for carrying out the above-described method for precise continuous control of air-fuel ratio in an endothermic engine, the device being suitably located in each of the following elements, namely the engine intake duct. a pressure sensor, a signal amplifier for amplifying the signal, a bandpass filter and a low-pass filter arranged to select the appropriate frequency range of the signal, from which the filter is tuned by a synchronization signal from a synchronization signal generator; a selector for splitting the signal from the selector, two peak measuring instruments receiving the signal from the selector and processing the received signal from the selector in accordance with a timing signal provided by the synchronization signal generator; an adder, for example in the form of a microprocessor, arranged to receive the signal from the adder and to process the received signal in a predetermined permanent manner; a correction device for correcting the air-fuel ratio according to an indication provided by the computing device;
Equipped with.

No J? The parameter Δp is a function of the pressure in the cylinder during the intake phase, and therefore of the piston speed, which experiences any fluctuations under rotational conditions, and the fluctuation port is a function of the periodic It also includes those caused by combustion fluctuations.

Combustion anomalies cause variations in the air flow rate and therefore intake pressure, which intake pressure variations can be made to be correlated with combustion variations.

[Basic theory of the present invention]

It is known that during engine operation each cylinder inhales an amount of air and fuel, and that the amount of air is proportional to the pressure in the intake manifold.

In particular, according to the applicant's bench test research, there is a difference between the pressure value detected by a pressure sensor properly placed in the intake manifold and irregular combustion phenomena due to an inaccurate air-fuel ratio. It has been found that there is one correlation.

In order to check the method described above, the applicant conducted experiments directly on a car placed on a roller ped. By controlling the amount of fuel supplied in each phase by means of a suitable electronic control unit, the applicant has made the amount of fuel dependent on the various air-fuel ratios at a constant rotational speed and the intake manifold. The output signals from the pressure surge transducers placed in communication were recorded on magnetic tape.

The intake manifold pressure was measured by the amount of air pumped into the manifold under the suction action of each cylinder.

The flow rate of air sucked into each cylinder and flowing through the seat of the intake pulp is expressed by the following function: &1.

G=f(A, ni, ρ, Δp, n) Here, G is the flow rate, M is the area of 4, and K is the ratio of specific heat c.
p, 'cr, ρ are the density, Δp is the pressure difference before and after the valve, 1(
.

is the valve opening time.

Although the air flow rate depends on several parameters, and this parameter also affects fuel fluctuations, the air flow rate increases when the engine is supplied with a very lean air-fuel mixture, which can cause instability. cause a feeling of

DETAILED DESCRIPTION OF THE INVENTION In the following, the invention will be explained in detail by way of purely non-limiting example and with reference to the accompanying drawings, in which: FIG.

In FIG. 1, reference symbol (C) indicates an intake duct of an internal combustion engine.

According to the invention, a pressure sensor (1) is placed in communication with the intake duct to generate a pressure signal, which pressure signal is suitably amplified by an amplifier (2).

It is filtered by a band pass filter (3) and then by a low pass filter (4).

A measurement channel selector 15) divides the signal and sends the divided signals to two peak measuring devices (61) and (62).

Fonic wheel (F5 is keyed to the drive shaft and rotates 180° in synchronization with each top dead center)
It outputs one pulse every time.

These pulses are sent to a synchronization signal generator (9).

The data adder is shown as (7). The adder 7 adds the displayed values of the peak measuring devices C61) and (62) based on the synchronization signal received from the synchronization signal generator (9).

The microprocessor (10) stores predetermined values of the air-fuel ratio. This value is determined by appropriate surface tests on the engine, corresponds to optimal measurements for all conditions of engine operation, and is specified in terms of speed under load.

In use, the signal from the sensor (1) is filtered (
3) and (4) after the selector (5)
sent to. In particular, the filter (3) removes frequency components lower than 2 Hz and higher than 200 Hz. The maximum frequency value corresponds to an engine speed of 6,000 revolutions. The filter (4) removes frequency components higher than the engine rotation speed, so the cutoff frequency changes in synchronization with the engine rotation.

According to the invention, the selector (5) receives the signal suitably F-waved by the filters (3) and (4) from the pressure sensor (1), separates it, divides it for each engine phase and The peak measuring device (61) and (62)
send to Splitting the signal is necessary to allow the information to be provided as completely as possible.

The indicated values provided by the peak measuring devices (61) and (62) are serialized by a suitably synchronized adder (7) (by a synchronizing signal generator (9)) and are used to predetermine the air/fuel ratio. microprocessor (10) in which stored values are stored;
sent to. At the output of the 7' adder (7) there appears a voltage level that is proportional to the irregularity of the engine's intake pressure and is therefore suitable for calculating its stability.

A display value is obtained from the comparison of the detected value with the stored value, which display value corresponds to the operating state of the engine, and a correction device (8) is therefore intervened to correct the display value in a closed loop. This applies to whether or not it is necessary to do so.

In the embodiment shown in FIG. 2, the signal from the amplifier 12) is F-waved by a single filter (11). This filter is configured to perform the functions performed by filters (3) and (4) in the embodiment of FIG.

In the schematic diagram shown in FIG.
The F-wave signal produced by
) and shown in FIG. 1 is not necessary. Therefore, the peak measuring device (12) processes the signals from the synchronization signal generator (9) and filters them (12).
Compare this with the value displayed on the micro
The micro sensor (10) sends the displayed value to the correction device (8).

The advantages of the invention will be apparent from the foregoing description.

According to the present invention, it is possible to easily and inexpensively provide a reliable operating device that can monitor and/or self-correct abnormal conditions related to the air-fuel ratio in an internal combustion engine. The techniques used to carry out the invention include:
It is particularly economical and compatible with current automobile production requirements.

Finally, it is clear from the foregoing description that various modifications can be made to the method and apparatus according to the invention without departing from the scope of the invention.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a device used to carry out an air-fuel ratio monitoring method in an internal combustion engine as an embodiment of the present invention, and FIG. 2 is a diagram showing a modification of the device shown in FIG. 1. 1: Pressure sensor, 2: Amplifier, 3: Bandpass filter, 4:
Low-pass filter, 5: Selector, 61° 62: Peak measuring device, 7: Adder, 8: Correction device, 9: Synchronous signal generator,
10: Calculating device, C: Intake duct, F: Huoni, Kuwheel Patent applicant Fiat Auto Soceta Per Azioni Patent attorney Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Masashi Matsushita Akira Yamaguchi Patent attorney Dr. Masaya Nishiyama Procedural Amendment (Method) Manabu Shiga, Commissioner of the Japan Patent Office in June 1985 1, Indication of the case 1985 Patent Application No. 22064 2, Name of the invention Air flow during operation of internal engine Method and device for monitoring fuel ratio 3, relationship with the case of the person making the correction Patent applicant name FIAT AUTO SOCHETA BE! Rare Tsuioni 4, Agent 5, Date of amendment order // 160. Sales 60 August 28th (shipping date) ＼ 6, Subject of amendment Figure 31, side 7, contents of amendment 11 + 121 As attached (31 @ cleaning (no change in contents) 1 letter

Claims (1)

[Claims] 1. A method for monitoring the air-fuel ratio during operation of an internal combustion engine, which method includes the following steps: measuring the pressure of air in the intake duct during operation of the internal combustion engine; processing the pressure signal in order to measure the variation value from one cycle to the next caused by the irregular combustion phenomenon; storing the predetermined value in correspondence with the optimum operating value; It is characterized by comprising the steps of: displaying that an irregular phenomenon exists in the air-fuel ratio when the value corresponding to the measured pressure fluctuation deviates from the stored value; and correcting the air-fuel ratio. A method for monitoring the air-fuel ratio during operation of an internal combustion engine. 2. A device for monitoring the air-fuel ratio during operation of an internal combustion engine, which device includes the following elements: a pressure sensor (
1), a signal amplifier (2) for amplifying the signal; a bandpass filter (3) and a low-pass filter (4) arranged to select the appropriate frequency range of the signal; from the filter (3, 4); A selector (
5) two peak measuring devices (61 #62) that receive a signal from the selector (5) and process the signal according to a timing signal supplied from the synchronization signal generator (9); an adder (7) suitably synchronized by a synchronization signal generator (9), receiving a signal from the adder (7) and comparing the signal with a predetermined permanently stored value; , characterized in that it comprises a computing device (10), for example in the form of a microprocessor, and a correction device (8) for correcting the air-fuel ratio according to the display provided by the computing device (10). A device that monitors the air-fuel ratio during engine operation. 3. Device according to claim 2, characterized in that it includes a single selection filter (11) for performing band F-wave and low-band filter functions. 4. Device according to claim 2, characterized in that it comprises a single peak value measuring device (12).